Hendry County Extension PO Box 68 LaBelle, Florida 33975-0068Phone (863) 674-4092
February 19, 2007
What a weather roller coaster the past month has been! Hot and cold, wet and dry and back again. A pair of strong cold fronts this past weekend bought the lowest temperatures of the season to most parts of south Florida bringing widespread frost to many areas on Saturday morning and again this morning in contradiction of El Niño predictions of decreased probability of winter freezes for Florida. This is quite a contrast to last month, which was one of the warmest on record.
All areas reported significant rainfall for the period most of which accumulated on several distinct events associated with unsettled weather and frontal passage. Highest accumulations were reported from Balm, followed by Fort Lauderdale, Homestead. In addition to rain, fog and heavy dews and periods of mostly cloudy weather has continued to favor disease development in many areas over the past few weeks.
Back to back frosts beginning and ending this past weekend caused varying amounts of crop damage across the area – most growers in South Florida escaped serious damage. The major exception being around Belle Glade where thousands of acres of corn and beans where reported severely damaged or destroyed by temperatures as low as 24o F.
FAWN Weather Summary
Date / Air Temp °F / Rainfall / Hours Below Certain Temperature (hours)Min / Max / (Inches) / 40°F / 45°F / 50°F / 55°F / 60°F / 65°F / 70°F / 75°F
Balm
1/12 – 2/19/07 / 31.2 / 77.4 / 4.24 / 19.3 / 3.9 / 30.3 / 5.1 / 37.7 / 63.6 / 154.4 / 217.9
Ft Lauderdale
1/12 – 2/19/07 / 39.6 / 87.3 / 2.99 / 0.3 / 9.2 / 11.9 / 20.6 / 34.2 / 8.1 / 34.3 / 51.5
Fort Pierce
1/12 – 2/19/07 / 31.5 / 83.9 / 0.35 / 14.7 / 3.8 / 36.7 / 20.9 / 13.3 / 3.3 / 47.2 / 154.4
Homestead
1/12 – 2/19/07 / 32.4 / 84.7 / 1.80 / 1.1 / 6.0 / 13.8 / 8.9 / 0.7 / 19.3 / 44.1 / 79.5
Immokalee
1/12 – 2/19/07 / 30.8 / 84.2 / N/A / 11.8 / 30.0 / 16.2 / 2.9 / 7.1 / 24.5 / 21.5 / 102.6
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COOPERATIVE EXTENSION WORK IN AGRICULTURE, FAMILY AND CONSUMER SCIENCES, SEA GRANT AND 4-H YOUTH, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA, U.S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING
Crops coming to market include cabbage, celery, cucumbers, eggplant, endive, escarole, lettuce, okra, parsley, peppers, radishes, snap beans, squash, strawberries, sweet corn, tomatoes, and specialty items. Quality is mostly good. Strawberry producers are glad for cooler temperatures in February, which favor berry development and growth.
The short-term forecast from the National Weather Service in Miami calls a gradual warming trend through the coming week with daytime highs reaching into the 80s by weekend and nighttime lows in the 40’s, 50’s, and 60’s towards weekend. For additional information, visit the National Weather Service in Miami website at
Insects
Whiteflies
Reports from Homestead indicate that whitefly pressure has been heavy.Some growers indicate that they are having a trouble achieving control with Admire, Provado, Knack and other common insecticides. TYLCV and Bean Golden mosaic are becoming more prevalent.
Respondents on the East Coast indicate that whitefly numbers are moderate to heavy in tomato and on newly planted squash and cucumbers especially those located near older tomato fields. Some problems with silverleaf have been noted in squash.
Light whitefly activity is being reported in most fields around Manatee County with numbers diminished by recent cold snaps. Reports of whitefly on regrowth in abandoned fields, which is now cleaned up for the most part has been received and growers expect that whitefly numbers will rebound once the weather warms.
Around Immokalee, whiteflies are moving around between fields and farms and numbers are going up in most locations. TYLCV symptoms are also becoming more common and we are starting to see the start of some typical spring flare up of this virus.
Some growers around Immokalee have commented that whiteflies appear to be coming out of the woods and that TYLCV incidence is often surprisingly high in relatively isolated fields.
Commenting on this observation, Dr Phil Stansly, Entomologist at UF/IFAS Southwest Florida Research and Education Center in Immokalee comments while this may seem to be the case to growers that in a two year study using yellow sticky traps, whitefly movement was generally from crops to weeds except at the beginning of the fall planting season.
Given that TYLCV has a relatively broad host range that does include some weeds, but with whiteflies generally going the other direction, weeds are probably not a primary sources of virus except possible in the very early season.
Phil comments further that while whiteflies and other small plant feeding insects are able to make short flights from plant to plant within a given field on their own, they are forced to attempt longer flights when they find themselves surrounded by senescing plants. This often results in them being carried up in air currents including thermals to where they are carried pretty much passively in the breeze with no more control than either to fly or not.
Cypress heads and wooded areas act as barriers to the wind current a good distance above the ground, reducing air velocity and causing turbulence and downdrafts. The whiteflies then settle around these obstacles just like fine sand around a stone in a stream. Following the fall harvest, whiteflies carrying virus from infected fields become airborne moving long distances in the winds to later descend around cypress heads and tree lines – seemingly coming out of the woods to initiate new foci of virus infection.
Thrips
Respondents on the East Coast are reporting serious problems with western flower thrips (Frankliniella occidentalis) in numerous locations from Fort Pierce to Boca Raton. Sources indicate that the thrips species have been positively identified by reputable sources.
Growers and scouts are reporting problems with heavy infestations on pepper, eggplant, tomato, cucurbits and specialty items like basil and cilantro. Damage includes etching and russeting of fruit and foliage. Reports indicate that growers are able to beat them back but have had difficulty in obtaining long-term control. Problems are said to be worse in planting close to older existing fields.
Around Immokalee, thrips are becoming a little more common but so far counts per bloom have been very low and crop damage negligible. Unlike the situation on the East Coast it appears like nearly all are Florida flower thrips (Frankliniella bispinosa).
A few thrips are also showing up around Manatee County.
Chilli thrips (Scirtothrips dorsalis) was detected in Florida in 2005. It has since been found throughout South and Central Florida mainly on ornamentals. It has been recorded throughout the world from over 100 hosts including tomato, pepper, strawberry, soybean, peanut, banana, bean, eggplant, castor beans (see for full host list).
It is extremely difficult to differentiate chilli thrips from other thrips in the field. Feeding can severely deform leaves and/or fruits, leaves and flower buds can drop, or leaf tissue can look scraped. Leaf symptoms can resemble broad mite damage. This thrips has also been reported to transmit several viruses. If you believe you have chilli thrips, please contact your local extension agent or the Cooperative Agricultural Pest Survey:
Leafminer
Growers and scouts in around Southwest Florida report that leafminer pressure continues to be “horrible” with some growers are calling it one of the worst years ever and scouts reporting that they just keep coming even though they have killed millions. Leafminer pressure continues to be high in a variety of crops including tomato, cucurbits, eggplants, beans and peppers. Adults are moving from older plantings in younger fields and new waves of larvae are common in young tomatoes.
Reports from Homestead, indicate that leafminer are widespread and causing problems in tomato, squash, bean and other crops.
Around the Manatee/Ruskin area, light leafminer activity is being reported in most fields.
Respondents in Palm Beach report that leafminer pressure has eased up in most places over the past few weeks.
Reports from around Belle Glade indicate that leafminer adults are working overtime on sensitive leafy vegetables. Respondents indicate that several of the spring mix type leafy vegetables are showing elevated levels of stippling due to female leafminers.
Leafminers attack many row crops but are particularly damaging on celery, crucifers, cucurbits, okra, potato and tomato. Florida growers report that leafminers are the second most important tomato insect pest especially in south and central production areas. Leafminers are present for much of the year in Florida. In south Florida, populations peak between October and March while in central Florida they are a problem in both spring and fall.
Leafminer injury is readily visible to the grower but healthy plants can tolerate considerable damage without excessive loss of vigor and yield. The Florida Tomato Scouting Guide sets action thresholds at 0.7 larva per plant for young plants with less than 2 true leaves and 0.7 larva per 3 terminal leaflets for larger plants. Heavily damaged leaves will often drop, due in part to entry of pathogenic organisms into old mines.
An integrated pest management program that stresses conservation of natural enemies is the primary tactic for the successful control of leafminer. Chemical control is difficult due to the feeding habits inside the leaf of the host plant. Insecticides that specifically target the leafminer are recommended as use of broad-spectrum materials may decimate beneficial insects including those that attack leafminer. This often results in a larger leafminer problem if the pesticide reduces field densities of leafminer parasites.
Fortunately, populations are usually prevented from reaching truly damaging levels by a number of parasites that attack leafminers. Several parasites for this insect have been recorded in Florida, but parasitic wasps such as Opius, Diglyphus are most common. Wasp larvae develop on or in the leafminer larva or pupa. The host ceases to feed and the parasitoid egg or larva is visible through the leaf epidermis using a hand lens against strong light. In scouting fields, growers should be careful to note the number of parasitized mines before deciding to apply insecticides.
Due to its feeding habit, this pest is resistant to many insecticides. Cyromazine (Trigard) alternated with abamectin (Agrimek) are effective against leafminer in tomato. Both of these products have limited crop registrations and must not be used on unregistered crops. Spinosad (Spintor, Entrust) has also given good results and is labeled on a wide range of crops. Some other materials that may be used to conserve beneficials include azadirachtin (Neemix) and insecticidal oils. Neemix and Entrust are approved for use by organic growers.
Field sanitation is an important control tactic that is overlooked. When crops are not present in the fields, leafminers can survive on a variety of broad-leaf weeds. These plants serve as reservoirs for pest.
Doug Restom Gaskillof the FDACS Cooperative Agricultural Pest Survey (CAPS) Program reports the California pea leaf miner (Liriomyza langei - formerly L. huidobrensis) is not established in Florida, but is a serious pest of many crops in California where it has become difficult to control. Unlike leaf miners known from Florida, which produce irregular serpentine mines in the leaf, the California pea leaf miner mines on the lower surface of the leaf near the midrib and lateral veins. Frass is deposited in a thin line down the middle of the mine. The host range is broad and includes tomato, pepper, potato, melon, pea, bean, celery, lettuce (see links below for full host list).
If you believe you have the California pea leaf miner, please contact your local extension agent or the Cooperative Agricultural Pest Survey:
Worms
Around Southwest Florida, growers and scouts indicate that although worm pressure has eased somewhat over the past few weeks pressure has remained steady into the New Year, with new egg masses being found this past week. Reports from chemical vendors confirm this indicating that based on levels of Bt sales this fall and winter has been a “wormy” one. Main species include southern and beet armyworms and loopers.
Respondents around Manatee County report that worm pressure remains mostly low with very few eggs and egg masses being detected by scouts.
On the East Coast growers and scouts report s indicate that worm pressure is mostly low with a few exceptions. Some problems have been noted with pickleworms in cucumbers planted close to older fields and scouts report that pinworms are building in a few places on tomato and eggplant.
Aphids
Around Immokalee, aphid pressure is increasing in several crops.
Reports from Palm Beach County indicate that few winged aphids are being detected but note that colony formation is present in a number of crops including eggplant, pepper squash and specialty items including oriental brassicas.
Around Manatee County, a few aphids are being detected in sticky traps and low levels are present in some fields.
Broad Mites
Growers and scouts on the east coast indicate that broadmites are still around and causing some problems in eggplant and pepper.
Around SW Florida repots indicate that broadmites are present in low numbers in a number of places and could flair up under the right conditions.
Note: Chilli thrips (Scirtothrips dorsalis) feeding damage at times resembles broadmite damage. If you are having difficulty with broadmite damage, you may want to check to see if you are having problems with chilli thrips.
Pepper Weevil
Around Southwest Florida, pepper weevil numbers are building in several older fields and new infestations are showing up in spring plantings.
Reports indicate that weevil numbers are being to build around Palm Beach County.
Diseases
Late Blight
Late blight continues to plague growers around Southwest Florida and is widely present across the area. Favorable conditions over the past month to six weeks have contributed to the high level of pressure being reported by growers.
Although many growers report that they have been successful in keeping late blight "contained", this is a relative term as disease occurrence and severity is a function of the presence of a pathogen (late blight innoculum is wide spread at this point), a susceptible host (plenty of tomatoes and potatoes out there) and a favorable environment. Environmental conditions for the development of late blight have been very favorable since Thanksgiving with heavy dew, numerous foggy morning and scattered showers at frequent intervals, which has undoubtedly contributed to the severity of the outbreak. Under such conditions, even seeming dry inactive lesions are capable of flare back up and becoming active when environmental conditions change.
There have been reports of several fields around Immokalee that were destroyed because disease levels were so high and many others with very bad late blight problems. There have been multiple reports of infected transplants coming from a number of transplant houses so growers would be well advised to examine plants carefully.
Some growers report that they have had to work like crazy to gain control but there are some locations where the growers have never really gotten ahead of the disease. Spraying once a week will never control it.
Scout also report finding late blight on volunteers around the entire area, on volunteers in row middles, around field edges and in fallow areas. Some of those little tomato volunteers that sprout up along the end of the beds prior to planting can and are developing late blight symptoms before the crop is planted. There have also been a number of reports of late blight on transplants
Reports from SW Florida indicate that organic producers have been having a particularly hard time with the disease.
Respondents on the East Coast report that they are also beginning to find late blight infections in a number of widely scattered locations from potatoes in Martin County to tomatoes from St Lucie County down to Palm Beach.
Respondent in Homestead report that late blight has been confirmed in Homestead and is spreading rapidly in tomato. Late blight has also been diagnosed on eggplant fruit.
Presence of late blight has also been confirmed in West Central Florida.
Late blight can easily devastate a tomato or potato field within a few weeks if it is not properly controlled. Since the disease can spread so rapidly, growers should scout their fields thoroughly each day, especially when cool and wet conditions conducive to disease development prevails. Since late blight symptoms may be confused with symptoms of other diseases, the following diagnostic pointers may help growers distinguish between the late blight and other diseases.